Specifically, the Daily Caller report said that Craig Woods, a former executive inside Missouri Equity Investors LLC JA Shepard Companies, said McCaskill's husband, Joseph Shephard, used the dining room to entertain investors. The McCaskill campaign has denied that there's any truth to Woods's claims.

The voiceover in the ad goes on to mention a separate report which noted that until recently McCaskill owed almost $300,000 worth of back taxes on her private plane, which McCaskill said she plans to sell.

"It's no surprise that McCaskill thinks she's above the law, she didn't pay her taxes but voted to raise ours. The arrogance and corruption of Claire McCaskillClaire McCaskillRNC drops six-figure ad buy for Supreme Court, healthcare fight Red-state Dems in Supreme Court pressure cooker Top GOP super PAC targets Manchin in first 2018 ad MORE," the voiceover continues. "Dealing herself in. Selling us out."

Recent polling has shown McCaskill leading Akin.